1. Field of the Invention
The present invention relates to a camera which uses a film having a magnetic memory and which has a magnetic head for writing/reading information to and from the magnetic memory.
2. Related Background Art
Hitherto, a camera using a film having a magnetic memory therein has been proposed. The camera has a means for intermediately rewinding the film before exposure of all frames. In a case where the intermediate rewind of the film has been performed, information concerning the frame finally exposed. When the film, which has been intermediately rewound is retained, is again loaded in the camera, the film is automatically wound till the frame which is the first unexposed frame of the film. Then, photographing becomes possible from the aforesaid first unexposed frame (refer to, for example, U.S. Pat. No. 4,864,332 and U.S. Pat. No. 4,965,600).
In a camera of the above described type capable of intermediately rewinding the film, the film can be loaded in the camera and it can be intermediately rewound so far as there is any remaining unexposed frame. When the loaded film is fed, the film moves forward while being rubbed by the inlet/outlet port of the cartridge and with a portion between the pressure plate and the rails. Furthermore, since strong frictional force acts on the film by a pressing roller of the spool, the surface of the film is damaged with thin scratches and the number of scratches increases in proportion to the number of such rewind operations. Therefore, the scratches become distinctive in a case where the film is developed, printed and especially enlarged, and the quality of the picture thus photographed becomes defective.
The film cartridge for use in the aforesaid camera has an indication means for indicating the condition of the film. The aforesaid disclosure made in U.S. Pat. No. 4,965,600 has an indication changeover means for changing over the indication means of the film cartridge. After the film has been rewound, the indication changeover means causes the indication means to indicate "all frames are unexposed frames" in a case where none of the frames has been exposed, to indicate "all frames have been exposed," in a case where all frames have exposed and to indicate "only partial frames have been exposed" in a case where only some of the frames have been exposed and there remain unexposed frames.
The structure according to U.S. Pat. No. 4,947,197 is arranged in such a manner that the indication "only partial frames have been exposed" is not made but the two indications "all frames are unexposed frames" and "all frames have been exposed" are made in order to simplify the indication changeover means.
However, in the latter conventional structure, the indication means of the film cartridge indicates ""all frames have been exposed" even if only one frame has been exposed. Therefore, a distinction from the film cartridge indicating "all frames have been exposed" cannot be made. As a result, a problem arises in that a user cannot again load the film cartridge having frames the major portion of which have not been exposed, and therefore all of the residual unexposed frames cannot be used.
According to the former conventional structure, the indication means of the film cartridge indicates "only partial frames have been exposed" even if only one unexposed frame remains. Therefore, a user again loads the aforesaid film cartridge to use the unexposed frame. However, the film must be fed until the unexposed frame of the film faces the aperture of the camera in order to expose the unexposed frame. Accordingly, it takes a long time to photograph only one frame or several frames, which causes a fear of a loss of a precise shutter chance. Besides, if a film cartridge having only one or several unexposed frames and having the indication means which indicates "only partial frames have been exposed" is loaded in the camera, what is even worse, all of the unexposed frames are undesirably exhausted although the desired number of frames has not yet been photographed. In this case, the user must rewind the aforesaid film cartridge and again load a new film cartridge, which causes an excessively complicated operation.